Thread: CNS-80 VNAV
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  #5  
Old October 25th 04, 04:37 PM
John R. Copeland
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If nobody else runs the test before I get a chance, I'll report back =
when I do.
I think you're too deep into speculation mode when you suggest baro =
input
might contribute to determination of lateral position.
Until I see some test results, I lean more toward thinking the CNX-80
may be relying on WAAS-augmented geometry for VNAV guidance.
It might be very ILS-like in that instance, where the baro setting
affects the DH(DA), but not the glide path.
---JRC---

"Dave Butler" wrote in message =
...
John R. Copeland wrote:
=20
I could test that by setting a grossly inaccurate Baro reading,
and watching the actual altitudes it steers me toward.
I think I'll try that next time I get a chance.

=20
I'll admit I'm guessing here, and I'd like to know exactly how the =

baro input is=20
incorporated in the navigation solution, but I suspect the baro =

altitude is=20
incorporated into the solution in a similar way to having another =

satellite in view.
=20
IOW, with 5 satellites in view plus baro input, the navigation =

solution has 6=20
equations with 4 unknowns (3 dimensional space plus time). If that's =

the case,=20
the baro input participates in the lateral position determination as =

well as the=20
vertical. I suppose they could "weight" the effect of the baro input =

since its=20
precision/accuracy are different from the satellite inputs.
=20
In TSOC129 units that use baro-aiding, there's no vertical guidance, =

yet the=20
baro input is incorporated in the navigation solution somehow.
=20
DGB